Gearbox case with wear sleeve

ABSTRACT

A gearbox may include a gearbox case with a wear sleeve disposed within a shaft bore, and a gear assembly mounted on a shaft and disposed within the shaft bore. The gear assembly may include a bearing that engages the wear sleeve. A method of repairing a gearbox case may include uncoupling a top piece and a bottom piece of the gearbox case, forming an oversize bore in a shaft bore of the gearbox case to remove a damaged area, and installing a wear sleeve in the oversize bore.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/807,456 filed Feb. 19, 2019, and entitled“Gearbox Case With Wear Sleeve”, which is incorporated herein byreferenced in its entirety.

TECHNICAL FIELD

The present disclosure relates to a gearbox case, and more particularly,to a gearbox case with wear sleeves in the shaft bores. The presentdisclosure also relates to a method of repairing a gearbox case byinstalling wear sleeves in the shaft bores.

BACKGROUND

Gearboxes are used in many industrial applications to transfer energyfrom one device to another. Gearboxes function to increase torque to anoutput shaft while reducing the speed of an input shaft. Thus, theoutput shaft of a gearbox rotates at a slower speed, but with anincreased torque resulting from the mechanical advantage produced byreducing the speed across the gearbox.

SUMMARY

The present disclosure is directed to a gearbox case that includes awear sleeve disposed within a shaft bore. The gearbox case may comprisea top piece and a bottom piece that are coupled together to form theshaft bore. The shaft bore may include an oversize bore adapted toreceive the wear sleeve. The depth of the oversize bore may besubstantially equal to a wall thickness of the wear sleeve such that thediameter of the shaft bore is substantially uniform across its length.In an implementation, the wall thickness of the wear sleeve is 6.35 mm¼-inch).

In an implementation, the oversize bore may further include acounterbore adapted to receive a lip of the wear sleeve. The interactionbetween the counterbore and the lip of the wear sleeve may retain thewear sleeve within the shaft bore and may inhibit longitudinal movementof the wear sleeve within the shaft bore during operation of thegearbox.

The length of the wear sleeve may be substantially equal to or greaterthan the length of a bearing to be installed in the shaft bore that willengage the wear sleeve. The wear sleeve material may have a strength andwearability that is equal to or greater than the gearbox case material.In an implementation, the wear sleeve is formed of 4140 heat treatedsteel. In another implementation, the wear sleeve material may have astrength and wearability lower than the gearbox case material such thatthe wear sleeve functions as an engineered wear point.

In an implementation, the gearbox case further comprises a retaining pinextending radially inwardly from the counterbore, and the wear sleevefurther comprises a longitudinal retaining notch adapted to receive thepin. The interaction between the pin and the wear sleeve may retain thewear sleeve within the shaft bore and may inhibit rotational movement ofthe wear sleeve during operation of the gearbox.

In another implementation, the present disclosure is directed to agearbox that includes a wear sleeve disposed between a bearing andgearbox case material within a shaft bore.

In yet another implementation, the present disclosure is directed to amethod of repairing a gearbox case. The method may comprise uncoupling atop piece and a bottom piece of the gearbox case, forming an oversizebore in a shaft bore of the gearbox case to remove a damaged area, andinstalling a wear sleeve in the oversize bore. In an implementation, themethod further comprises forming a counterbore in the oversize bore,wherein the counterbore receives a lip of the wear sleeve wheninstalling the wear sleeve in the oversize bore. In an implementation,the method further comprises installing a retaining pin in the oversizebore before installing the wear sleeve, and engaging the retaining pinwith a notch in the wear sleeve during the step of installing the wearsleeve.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features,objects, and advantages of the implementations will be apparent from thedescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure and its features,reference is now made to the following description, taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 illustrates a front perspective view of an implementation of agearbox case with wear sleeves in the shaft bores, according to thepresent disclosure.

FIG. 2 illustrates a front perspective view of a portion of the gearboxcase of FIG. 1, according to the present disclosure.

FIG. 3 illustrates an enlarged perspective view of wear sleeves within asingle shaft bore of the gearbox case of FIG. 1, according to thepresent disclosure.

FIG. 4 illustrates a rear perspective view of an implementation of apartially assembled gearbox, depicting the bottom piece of the gearboxcase of FIG. 1 with gear assemblies installed within the shaft bores andbearings installed within the wear sleeves, according to the presentdisclosure.

FIG. 5 illustrates a front perspective view of an implementation of amore fully assembled gearbox, depicting the gearbox case of FIG. 1 withbearings installed within the wear sleeves, according to the presentdisclosure.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

A gearbox may include a series of integrated gears disposed within agearbox case. The gears are mounted on shafts positioned within shaftbores formed in the gearbox case. The shafts are supported within theshaft bores by rolling element bearings that allow the shafts and gearsto rotate.

In conventional gearboxes, these bearings engage the gearbox casematerial within the shaft bores. Over time, the bearings start to failand may become loose and/or cause wear on, and damage to, the gearboxcase material within the shaft bores, necessitating a maintenancerepair. The frequency of such maintenance repairs depends on howextensively the gearbox is used. In one example, a gearbox used for drawworks on a drilling rig, may require a maintenance repair every 2-3years.

A conventional method of making a maintenance repair is to plane thegearbox case. A gearbox case may include a top piece and a bottom piecethat are coupled together. To plane a gearbox case that has been worn ordamaged by interaction with the bearings, the two pieces of the gearboxcase are separated, then the interior flat areas of the gearbox case onboth the top piece and the bottom piece are milled down, and then theshaft bores are bored out to remove the worn and/or damaged areas and toresize the shaft bores appropriately to accommodate the bearings. Thisconventional repair method is time consuming, expensive, and challengingto complete accurately. In addition, because this method removesmaterial from the gearbox case each time, it can only be performed alimited number of times before the gearbox case must be replaced.

The present disclosure is directed to a gearbox case comprising wearsleeves in the shaft bores. In an implementation, the wear sleeves arepositioned within the shaft bores to engage the bearings. As such, asthe bearings fail, the bearings will cause wear and/or damage to thewear sleeves rather than to the gearbox case itself. In animplementation, the wear sleeves are removably installed within thegearbox case such that as the wear sleeves are worn and/or damaged bythe bearings, they can be replaced. During this repair, the gearbox casematerial remains intact since the gearbox case is not being planed, andmaintenance repairs can be completed indefinitely without requiringreplacement of the gearbox case.

Referring now to the drawings, where like reference numerals representlike components, FIG. 1 illustrates a front perspective view of animplementation of a gearbox case 100 according to the presentdisclosure. The gearbox case 100 comprises a top piece 110 and a bottompiece 120 coupled together, such as by bolt assemblies 130. The gearboxcase 100 further comprises a plurality of shaft bores 140, such as thefour shaft bores 142, 144, 146, 148. The gearbox case 100 also comprisesa set of wear sleeves 150, 160 for each shaft bore 140, such that a wearsleeve 150 is provided on a first end of each shaft bore 140, and a wearsleeve 160 is provided on the opposite end of each shaft bore 140. Asshown in FIG. 1, wear sleeves 152, 162 are provided on opposite ends ofshaft bore 142. FIG. 1 also depicts wear sleeve 154 in shaft bore 144,wear sleeve 156 in shaft bore 146, and wear sleeve 158 in shaft bore148.

FIG. 2 illustrates a front perspective view of a portion of the gearboxcase 100 of FIG. 1 with wear sleeve 154 removed. In an implementation,before installing the wear sleeves 150, 160 a larger diameter bore oroversize bore, such as oversize bore 141, is formed within the gearboxcase at each end of the original shaft bore 145 where the wear sleeves150, 160 will be installed such that the wear sleeves 150, 160 areretained within the oversize bores. Thus, before the wear sleeves 150,160 are installed, a multi-diameter bore is formed in the gearbox case100. The multi-diameter bore includes first and third sectionscorresponding to the oversize bores at each end, and a second sectioncorresponding to the original shaft bore 145 between the oversize bores.The oversize bores may have a depth substantially equal to the wallthickness of the corresponding wear sleeves 150, 160 such that when thewear sleeves 150, 160 are installed within the oversize bores, the innerdiameter of the wear sleeves 150, 160 align with the original shaftbores 145 therebetween to form the shaft bores 140 that aresubstantially uniform across their length.

In an implementation, adjacent an end of each of the oversize bores thegearbox case includes a counterbore, such as counterbore 143 shownadjacent the end of oversize bore 141. Each of the counterbores isadapted to receive a lip of the wear sleeves 150, 160, such as lips 153,155, 157, 159, 163, 165, 167, 169 of wear sleeves 152, 154, 156, 158,162, 164, 166, 168, as depicted in FIGS. 2-5. Therefore, when the wearsleeves 150, 160 are installed within the oversize bores at to form theshaft bores 140, the lips of the wear sleeves 150, 160 are retainedwithin the counterbores adjacent the oversize bores. This interactionaids in keeping the wear sleeves 150, 160 in place within the oversizebores and inhibits the wear sleeves 150, 160 from moving longitudinallyinto the shaft bores 140 during operation.

The gearbox case 100 depicted in FIG. 1 is for a triple-reductiongearbox that may be used, for example, on an AC-drive 1500 Horsepowerdraw works on a drilling rig. The draw works is a hoisting mechanismwith a big spool that raises drilling equipment out of a well bore in adrilling environment. The 1500 Horsepower electric motor input shaftextends into the smallest shaft bore 148 and spins at about 1000revolutions per minute (rpm). The 1000 rpm from the input shaft isreduced twice by gear assemblies (shown in FIGS. 4 and 5) that extendinto the middle shaft bores 144, 146 before reaching the output shaftextending from the largest shaft bore 142 to turn the draw works winchdrum at approximately 250-300 rpm and a higher torque achieved by themechanical advantage obtained through the speed reduction.

In an implementation, the gearbox case 100 may further comprise aretaining pin 170 extending radially inwardly from the bottom piece 120within each oversize bore. As the wear sleeves 150, 160 are installed inthe oversize bores, the retaining pin 170 may be received within alongitudinal notch 180 formed in the wear sleeves 150, 160, such as wearsleeve 156 depicted in FIG. 2.

In more detail, FIG. 3 illustrates an enlarged perspective view of thewear sleeves 154, 164 installed within oversize bores formed at oppositeends of the original shaft bore 145 to form shaft bore 144 of thegearbox case 100 shown in FIG. 1. As depicted in FIG. 3, retaining pin172 is disposed within longitudinal notch 182 of wear sleeve 154, andretaining pin 174 is disposed within longitudinal notch 184 of wearsleeve 164 on the opposite end of shaft bore 144. The retaining pin 170and notch 180 interaction aids in keeping the wear sleeves 150, 160 inplace within the oversize bores and inhibits the wear sleeves 150, 160from turning with respect to the gearbox case 100 during operation.

FIG. 4 illustrates a rear perspective view of an implementation of apartially assembled gearbox 200 with the bottom piece 120 of the gearboxcase 100 supporting gear assemblies 210, 220, 230 and 240 disposedwithin shaft bores 142, 144, 146 and 148, respectively. In thispartially assembled gearbox 200, bearings 212, 222, 232 and 242 areshown disposed within and supported by wear sleeves 162, 164, 166 and168, respectively. On the opposite end of gear assemblies 220 and 240,bearings 224 and 244 are shown disposed within and supported by wearsleeves 154 and 158, respectively.

FIG. 5 illustrates a front perspective view of an implementation of amore fully assembled gearbox 200, depicting the gearbox case 100 withbearings 214, 224, 234 and 244 installed within wear sleeves 152, 154,156 and 158, respectively.

In an implementation, the present disclosure is directed to a method ofrepairing a gearbox case. The method may comprise uncoupling a top pieceand a bottom piece of the gearbox case, removing a damaged area of thegearbox case by forming an oversize bore at the end of an original shaftbore of the gearbox case, and installing a wear sleeve in the oversizebore. The method may further comprise forming a counterbore in thegearbox case adjacent an end of the oversize bore before installing thewear sleeve, and receiving a lip of the wear sleeve within thecounterbore during the step of installing the wear sleeve. In animplementation, the method further comprises installing a retaining pinin the gearbox case in the oversize bore before installing the wearsleeve, and engaging the retaining pin with a notch in the wear sleeveduring the step of installing the wear sleeve.

It is to be understood the implementations are not limited to particularsystems or processes described which may, of course, vary. For example,the gearbox case 100 and the gearbox 200 depicted and described hereinmay be originally manufactured components, or they may result from arepair to a damaged gearbox that did not originally include the wearsleeves 150, 160. In addition, while gearbox case 100 is depicted asforming part of a triple-reduction gearbox 200, the teachings of thepresent disclosure may be applied to any two-piece (top and bottom)gearbox case.

It is also to be understood that the terminology used herein is for thepurpose of describing particular implementations only, and is notintended to be limiting. As used in this specification, the singularforms “a”, “an” and “the” include plural referents unless the contentclearly indicates otherwise. As another example, “coupling” includesdirect and/or indirect coupling of members.

Although the present disclosure has been described in detail, it shouldbe understood that various changes, substitutions and alterations may bemade herein without departing from the spirit and scope of thedisclosure as defined by the appended claims. Moreover, the scope of thepresent application is not intended to be limited to the particularembodiments of the process, machine, manufacture, composition of matter,means, methods and steps described in the specification. As one ofordinary skill in the art will readily appreciate from the disclosure,processes, machines, manufacture, compositions of matter, means,methods, or steps, presently existing or later to be developed thatperform substantially the same function or achieve substantially thesame result as the corresponding embodiments described herein may beutilized according to the present disclosure. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.

The invention claimed is:
 1. An apparatus comprising: a gearbox casewith a shaft bore extending therethrough; a first wear sleeve disposedwithin and coupled to the gearbox case at a first end of the shaft bore;and a second wear sleeve disposed within and coupled to the gearbox caseat a second end of the shaft bore; wherein an inner diameter of thefirst wear sleeve and an inner diameter of the second wear sleeve formpart of the shaft bore; and wherein the shaft bore has a substantiallyuniform diameter across its length.
 2. The apparatus of claim 1, whereinthe gearbox case comprises a top piece and a bottom piece that arecoupled together to form the shaft bore.
 3. The apparatus of claim 1,wherein at least one of the wear sleeves is adapted to engage a bearinginstalled in the shaft bore.
 4. The apparatus of claim 3, wherein the atleast one wear sleeve has a length substantially equal to or greaterthan the bearing.
 5. The apparatus of claim 1, wherein at least one ofthe wear sleeves is formed of a material having a strength equal to orgreater than a material forming the gearbox case.
 6. The apparatus ofclaim 1, wherein at least one of the wear sleeves is formed from 4140heat treated steel.
 7. The apparatus of claim 1, wherein at least one ofthe wear sleeves is formed of a material having a strength less than amaterial forming the gearbox case.
 8. The apparatus of claim 1, furthercomprising: a retaining pin extending radially inwardly from the gearboxcase; and a longitudinal retaining notch in the first or the second wearsleeve adapted to receive the retaining pin.
 9. The gearbox of claim 1,further comprising: a gear assembly mounted on a shaft and disposedwithin the shaft bore; wherein the gear assembly comprises bearings oneach end engaging the wear sleeves.
 10. The gearbox of claim 9, furthercomprising: a first oversize bore and a second oversize bore in thegearbox case; wherein the oversize bores are adapted to receive thefirst and second wear sleeves, respectively.
 11. The gearbox of claim10, wherein each of the first and second oversize bores has a depthsubstantially equal to a wall thickness of the first and second wearsleeves, respectively.
 12. The gearbox of claim 10, further comprising:a first counterbore formed in the gearbox case adjacent the firstoversize bore; and a second counterbore formed in the gearbox caseadjacent the second oversize bore; wherein the first and the secondcounterbores are adapted to receive a lip of the first and second wearsleeves, respectively.
 13. The gearbox of claim 9, wherein at least oneof the first and second wear sleeves has a length substantially equal toor greater than the respective bearing the at least one of the first andsecond wear sleeve engages.
 14. The gearbox of claim 9, wherein at leastone of the wear sleeves is formed of a material having a strength equalto or greater than a material forming the gearbox case.
 15. The gearboxof claim 9, wherein at least one of the wear sleeves is formed of amaterial having a strength less than a material forming the gearboxcase.
 16. The gearbox of claim 9, further comprising: a retaining pinextending radially inwardly from the gearbox case; and a longitudinalretaining notch in at least one of the wear sleeves adapted to receivethe retaining pin.
 17. An apparatus comprising: a gearbox case with amulti-diameter bore extending therethrough from a first side to a secondside of the gearbox case, the multi-diameter bore comprising: a firstsection having a first diameter and having a first length that extendsfrom the first side of the gearbox case into the gearbox case; a secondsection adjacent to the first section, the second section having asecond diameter and a second length that extends from the first sectionfurther into the gearbox case; and a third section adjacent to thesecond section, the third section having a third diameter and a thirdlength that extends from the second section to the second side of thegearbox case; a first wear sleeve disposed within and coupled to thegearbox case within the first section of the multi-diameter bore, thefirst wear sleeve having a length substantially equal to the firstlength, and an inner diameter substantially equal to the seconddiameter; and a second wear sleeve disposed within and coupled to thegearbox case within the third section of the bore, the second wearsleeve having a length substantially equal to the third length, and aninner diameter substantially equal to the second diameter.
 18. Theapparatus of claim 17, wherein the first diameter substantially equalsthe third diameter.
 19. The apparatus of claim 17, further comprising ashaft bore extending through the gearbox case, the shaft bore formed bythe inner diameter of the first wear sleeve, the second section of themulti-diameter bore, and the inner diameter of the second wear sleeve.